1. Field of the Invention
The present invention relates to an image input system suitable for use in an image communications system for transmitting and receiving images over a distance.
2. Description of the Related Art
Recently, as a result of the development of image compression/encoding techniques and the spread of high-speed/high-quality digital lines (such as ISDN (integrated services digital network)), there are various specific recommendations intended for video/audio services, such as a videoconference system, and various image communications systems that are in conformity with such recommendations are being developed.
Among such image communications systems is an image input apparatus (system) having a means for controlling or adjusting the image pickup direction of a moving image pickup apparatus such as a camera. In this system, an image pickup direction control key, provided on an operation panel, is used to send a control command to a system unit to cause the moving image pickup apparatus to rotate by an angle corresponding to the input control command. By this system, it is possible to control the image pickup direction of not only the image pickup apparatus at the user's end of the line but also the image pickup direction the image pickup apparatus at the other end of the line. The image pickup magnification of the image pickup apparatus can also be controlled in the same way.
When the orientation of the image pickup apparatus is adjusted, an image obtained by this image pickup apparatus is displayed on a display device, and the user operates image pickup direction control keys while watching the displayed image so as to orient the image pickup apparatus in a desired image pickup direction.
In a videoconference system, which is an example of such an image communications systems, the received image may be displayed as it is. However, when displaying a self-image of the user, a mirror image display (which is reversed left to right) is preferable since it is closer to the actual image that the user usually sees. Thus, a display device provided at a terminal of a videoconference system is equipped with a real image display form (mode) for displaying an image unreversed from left to right and a mirror image display form (mode) for displaying an image reversed from left to right.
Thus, when adjusting or controlling the orientation of the image pickup apparatus while watching the taken image displayed on an image display system which is equipped with a real image display form and a mirror image display form, the operation of an image pickup direction control key and the direction of swinging of the image pickup apparatus in response thereto are in a one-to-one correspondence. Thus, the reaction of the displayed image to the operation of an image pickup direction control key when the image is being displayed in the real image display form is reverse to the reaction of the displayed image to the operation of the same image pickup direction control key when the image is being displayed in the mirror image display form.
In more detail, the depression of an image pickup direction control key and the reaction of the image to the depression is in a one-to-one correspondence, as stated above. For example, when the RIGHT key of the image pickup direction control keys is depressed, the image pickup direction is changed to the right, and, when the LEFT key is depressed, the image pickup direction is changed to the left. This leads to a problem in the case of a self-image of the user displayed in the mirror image display form. For example, when the image pickup direction is to be changed to the right as seen from the user while displaying a self image of the user in the mirror image pickup form, the camera, which is directed to the user, has to be turned to the right as seen from the user. To effect this, the camera has to be swung to the left (as seen from the camera), so the user must depress the LEFT key of the image pickup direction control keys. However, the user often erroneously operates the RIGHT key, instead of the LEFT key, since the change to be effected in this case is "to the right" when seen from the user.
This will be specifically explained with reference to FIG. 15. FIG. 15 is a diagram for illustrating such swinging control in the prior art. FIG. 15(A) shows the control when the image is displayed in the real image display form, and FIG. 15(B) shows the control when the image is displayed in the mirror image display form. In either case, a camera 100 takes an image of the same person 102. The image of the person photographed by the camera 100 is displayed as it is on a screen 104 for real image display of FIG. 15(A), whereas the image displayed on a screen 106 for mirror image display (FIG. 15(B)) is reversed from left to right.
In the real image display form, when the image of the person is to be moved toward the center of the screen, a "LEFT" key 110 of image pickup direction control keys 108 is depressed, whereby the camera 100 is swung in the direction indicated by an arrow 114 to thereby cause the image of the person 102 to move toward the center of the screen. This swinging control, effected by the user while watching the image displayed on the screen 104, is well matched with the actual feeling of the user.
Things are different when the image is displayed in the mirror image display form. For example, to move the image of the person 102 which is at the right-hand end of the screen 106 toward the center of the screen, the user is inclined to depress a "RIGHT" key 112 of the image pickup direction control keys 108 since that is closer to the actual feeling of the user. However, if the "RIGHT" key 112 is depressed, the camera 100 is swung to the right (as seen from the camera 100), that is, in the direction indicated by the arrow 116, with the result that the image of the person is further shifted to the right in the screen 106, that is, pushed off the screen 106.
Thus, the control of the image pickup direction of the image pickup apparatus in the prior is not always matched with the actual feeling of the operator, and often leads to confusion.